Are you getting “Updating Aperture Videos Events” and iMovie just hanging?
Open your Aperture Library. (By clicking on Show the Package Contents)
Delete iMovie->Thumbnails and iLifeShared
I would also recommend running Onyx to clean your caches and repair permissions.
Don’t see your Aperture library in iMovie?
Open Aperture, > Preferences, and click Previews. In the “Share previews with iLife and iWork”